The present invention relates to bone grafts for use in the repair, replacement, and/or augmentation of various portions of animal or human skeletal systems. More particularly, the present invention relates to a prepared bone graft, guides for forming bone grafts and methods of forming bone grafts.
Several procedures involve the use and implantation of autograft bone, allograft bone or xenograft bone into an animal or human body. At least some of the benefits of implanted bone includes providing support, promoting healing, filling bony cavities, separating or spacing bony elements such as vertebral bodies, promoting fusion, and stabilizing the site of fractures.
In one known procedure, a donor bone from a cadaver is selected and prepared for insertion into a patient. For example, a spinal implant may be prepared by selecting a femur or tibia bone and cutting the bone to a desired shape. Alternatively, a portion of a bone can be cut from the patient receiving the implant, usually from a large bone such as a hip bone. In another known procedure, the bone graft can be a synthetic material which has been formed to a desired size and shape.
Typically, bone grafts are prepared outside the operating room in a production facility, and inserts are prepared having a variety of shapes and sizes so that the physician performing a bone implant operation can select a properly sized and shaped implant for each patient and procedure. Production of bone graft can be expensive because the production facility must be capable of producing sterile implants, and the bone graft must be stored prior to use in an operation.
For many procedures, it may be desirable to provide a roughened or irregular surface on at least one surface of the finished bone graft to promote fusion of the graft to adjacent bone in the body. In addition, during an operation requiring an insert having a very precise size and shape, for example, a discectomy and spinal fusion procedure, a surgeon must have on hand a variety of bone graft sizes and shapes to precisely fit the bone graft into the disc space of the patient after preparation of the bone graft, which may include surgical removal of a ruptured or degenerated disc or a portion thereof.
Presently known methods for preparing bone grafts have shortcomings. One shortcoming is the cost of manufacturing bone grafts and sterilizing and storing the bone grafts in a production facility. Another shortcoming is the difficulty of forming a roughened or irregular surface on a bone graft, particularly after the bone graft has been cut to a desired size and shape. Formation of the roughened or irregular surface typically requires machining after cutting of the bone graft, and this may alter the dimensions or shape of the bone graft.
In view of these and other shortcomings associated with providing bone grafts, it would be desirable to provide an improved method and apparatus for the manufacture of bone grafts. Such a method should be relatively simple, inexpensive and provide the flexibility of allowing the bone graft to be prepared intraoperatively in an operating room.
Accordingly, the present invention generally provides a relatively simple bone graft forming guide and a method of forming a bone graft. The method includes the steps of selecting the shape of at least a portion of a bone graft and forming a plurality of holes in a graft material. According to one aspect of the invention, the plurality of holes forms a pattern generally corresponding to the intended shape of the bone graft. The invention may further include cutting at least partially through the graft material along the pattern formed by the plurality of holes.
According to one aspect of the invention, the cutting step includes cutting through at least a portion of the plurality of holes resulting in a portion of the bone graft having a roughened surface. Another aspect of the invention includes providing a drill guide containing a plurality of hole guides arranged in a pattern generally corresponding to the intended shape of the bone graft. According to this aspect of the invention, the method includes positioning the drill guide with respect to the graft material and drilling into the graft material using a least a portion of the hole guides.
In another aspect of the invention, the method may further include providing a cutting guide having a pattern corresponding the intended shape of the bone graft, positioning the cutting device with respect to the graft material, and cutting the graft material using the cutting guide. In another aspect, the drilling step includes drilling through the graft material and the cutting step includes cutting through the graft material.
According to a preferred aspect of the invention, the method is performed intraoperatively in an operating room. This aspect of the invention provides the surgeon performing a bone graft insertion procedure with the flexibility to select a properly sized and shaped bone graft in the operating room. According to prior art methods, a surgeon would have to purchase various differently sized and shaped bone grafts that are fabricated in a facility outside the operating room. For example, according to one aspect of the invention, a spinal bone graft may be formed in a generally elliptical shape with respect to the cutting direction. According to this aspect of the invention, the hole guide and the cutting guide have a pattern that is generally elliptical in shape. According to another aspect of the invention, a spinal bone graft can be produced that is generally cut in a wedge shape.
Another aspect of the invention pertains to a method of forming a bone graft from a graft material including the steps of selecting the shape of at least a portion of the bone graft, providing a graft material holder and selecting from a plurality of cutting guides, each of the cutting guides having a different cutting pattern. According to this aspect of the invention, the method further includes associating the cutting guide with the graft material holder and cutting at least a portion of the bone graft material using the cutting guide.
Another aspect of the invention involves a bone graft forming guide for providing a bone graft having a desired shape. According to this aspect of the invention, the cutting guide has a main body including a holder for holding a graft material and a cutting guide-receiving structure. This aspect of the invention also includes a cutting guide containing a pattern corresponding to the desired shape of the bone graft, and the cutting guide adapted to be detachably mounted to the main body.
According to another aspect of the invention, the forming guide includes a main body having a holder for holding a graft material and a hole guide containing a plurality of hole guides arranged in a pattern generally corresponding to the desired shape of the bone graft. The forming guide further includes a cutting guide containing a pattern corresponding to the desired shape of the bone graft.
In one aspect of the invention, the hole guide is an insert and the main body includes a guide receiving opening to receive the insert. In another aspect, the cutting guide is an insert and the main body includes an opening to receive the insert. According to this aspect of the invention, the forming guide includes a securing mechanism for removably securing one or both of the hole guide insert or the cutting guide insert in the opening.
In a preferred embodiment, the securing mechanism includes a cam member associated with the main body. Preferably, the cam member cooperates with one or both of the hole guide insert or the cutting guide insert to secure one or both of the inserts to the main body. In another aspect of the invention, the hole guide insert and the cutting guide insert include a ridge adapted to cooperate with the cam member.
According to one aspect of the invention, the main body of the bone graft forming guide includes a block adapted to receive a graft material. Preferably, the block includes two members connected by a hinge. Preferably, the main body further includes a closure means such as a clamping mechanism for clamping the two members towards each other to secure the bone within the cutting guide. Preferably, the clamping mechanism includes a threaded rod and nut assembly.
According to another aspect of the invention, the forming guide includes a handle and a shaft having a proximal end and a distal end. The proximal end of the shaft is attached to the handle, and a pair of jaws extends from the distal end of the shaft. The jaws are movable between a gripping position to grip graft material during cutting of the bone graft and a releasing position to release the implant. According to this aspect of the invention, the handle includes pair of arms connected to the pair of jaws to provide a pair of gripping members that are pivotally joined. Preferably, the pair of arms includes a locking mechanism to lock the cutting guide in a plurality of positions. According to this aspect, the cutting guides are attached to at least one of the jaws. In a preferred aspect, the hole guide and the cutting guide are removable inserts. Alternatively, the hole guide and the cutting guide may be integrally formed in at least one of the jaws.
Another aspect of the invention relates to a bone graft forming guide including a handle and a shaft having a proximal end and a distal end. The proximal end of the shaft is attached to the handle, and a pair of jaws extends from the distal end of the shaft. According to this aspect of the invention, a cutting guide is associated with the jaws, and the jaws are movable between a gripping position to grip graft material during cutting of the bone graft and a releasing position to release the implant. Preferably, the handle includes a pair of arms connected to said pair of jaws to provide a pair of gripping members, the gripping members being pivotally joined.
The present invention provides a relatively simple and inexpensive way to make bone grafts. A surgeon can select a from a variety of hole guides and cutting guides to provide various sized and shaped bone grafts for a procedure. Advantageously, the method and forming guide of the invention can be used intraoperatively in an operating room setting. By forming a plurality of holes in the graft material prior to cutting of the graft material, a roughened surface is provided on at least one surface of the bone graft. In one preferred aspect of the invention, the hole guides contain round holes, and the cutting guide is positioned such that the cutting device cuts through the approximate center of the holes to provide a roughened or ridged surface on at least one surface of the bone graft. The roughened surface promotes ease of insertion of the graft and fusion of the bone graft to an adjacent bone after insertion in the body.
Additional features and advantages of the invention will be set forth in the description which follows. It is to be understood that both the foregoing summary and the following detailed description are exemplary and are intended to provide further explanation of the invention as claimed. In the following drawings, like reference characters denote similar elements throughout the several views.